On Derandomizing Local Distributed Algorithms

The gap between the known randomized and deterministic local distributed algorithms underlies arguably the most fundamental and central open question in distributed graph algorithms. In this paper, we develop a generic and clean recipe for derandomizing LOCAL algorithms. We also exhibit how this simple recipe leads to significant improvements on a number of problem. Two main results are: - An improved distributed hypergraph maximal matching algorithm, improving on Fischer, Ghaffari, and Kuhn [FOCS'17], and giving improved algorithms for edge-coloring, maximum matching approximation, and low out-degree edge orientation. The first gives an improved algorithm for Open Problem 11.4 of the book of Barenboim and Elkin, and the last gives the first positive resolution of their Open Problem 11.10. - An improved distributed algorithm for the Lov\'{a}sz Local Lemma, which gets closer to a conjecture of Chang and Pettie [FOCS'17], and moreover leads to improved distributed algorithms for problems such as defective coloring and $k$-SAT.Comment: 37 page

Computation of canonical correlation and best predictable aspect of future for time series

The canonical correlation between the (infinite) past and future of a stationary time series is shown to be the limit of the canonical correlation between the (infinite) past and (finite) future, and computation of the latter is reduced to a (generalized) eigenvalue problem involving (finite) matrices. This provides a convenient and essentially, finite-dimensional algorithm for computing canonical correlations and components of a time series. An upper bound is conjectured for the largest canonical correlation

SMUGGLING AS ANOTHER CAUSE OF FAILURE OF THE PPP

In theoretical literature, smuggling is considered as a factor contributing to the deviation of the PPP-based exchange rates from the equilibrium exchange rates with little empirical support. In this paper, we used panel data for 33 developing countries over the period 1982-1995 and used panel unit root and panel cointegration technique along with pooled OLS, fixed effects, random effects, and Parks estimator in an augmented Balassa-Samuelson framework. Using two different proxies for smuggling it is found that smuggling into a country leads to an appreciation of domestic currency that can be considered as another cause of loosing competitiveness by many developing countries.Smuggling, PPP, Real Exchange Rate, Panel Data, Panel Unit Root, Panel Cointegration, LDCs

Cayley's hyperdeterminant: a combinatorial approach via representation theory

Cayley's hyperdeterminant is a homogeneous polynomial of degree 4 in the 8 entries of a 2 x 2 x 2 array. It is the simplest (nonconstant) polynomial which is invariant under changes of basis in three directions. We use elementary facts about representations of the 3-dimensional simple Lie algebra sl_2(C) to reduce the problem of finding the invariant polynomials for a 2 x 2 x 2 array to a combinatorial problem on the enumeration of 2 x 2 x 2 arrays with non-negative integer entries. We then apply results from linear algebra to obtain a new proof that Cayley's hyperdeterminant generates all the invariants. In the last section we show how this approach can be applied to general multidimensional arrays.Comment: 20 page

Structure of Protoplanetary Discs with Magnetically-driven Winds

We present a new set of analytical solutions to model the steady state structure of a protoplanetary disc with a magnetically-driven wind. Our model implements a parametrization of the stresses involved and the wind launching mechanism in terms of the plasma parameter at the disc midplane, as suggested by the results of recent, local MHD simulations. When wind mass-loss is accounted for, we find that its rate significantly reduces the disc surface density, particularly in the inner disc region. We also find that models that include wind mass-loss lead to thinner dust layers. As an astrophysical application of our models, we address the case of HL Tau, whose disc exhibits a high accretion rate and efficient dust settling at its midplane. These two observational features are not easy to reconcile with conventional accretion disc theory, where the level of turbulence needed to explain the high accretion rate would prevent a thin dust layer. Our disc model that incorporates both mass-loss and angular momentum removal by a wind is able to account for HL Tau observational constraints concerning its high accretion rate and dust layer thinness.Comment: Accepted for publication in MNRAS, 13 pages, 8 figure

Baltimore Red Line Project: An Overview of the Cooks Lane Tunnel

The Maryland Transit Administration’s Baltimore Red Line is a proposed 14.1-mile east-west Light Rail Transit (LRT) line connecting the areas of Woodlawn, Edmondson Village, West Baltimore, downtown Baltimore, Inner Harbour East, Fells Point, Canton and the Johns Hopkins Bayview Medical Centre Campus. Red Line has two tunnel segments namely, the Downtown and the Cooks Lane Tunnels. The Cooks Lane Tunnel (CLT) is the shorter of the two tunnels and will connect the proposed at-grade LRT segment running alongside I-70 with the at-grade LRT segment along Edmondson Avenue. The western CLT portal will be west of the intersection of North Forest Park Avenue and Cooks Lane and the eastern portal will be in the median of Edmondson Avenue close to the intersection with Cooks Lane. The length of the CLT is approximately 7,100 feet inclusive of the cut-and-cover and retained cut sections at both ends. The proposed CLT will be excavated below water table and in a variety of ground conditions ranging from soft ground to competent rock. Variable geotechnical conditions, mixed-face tunnel excavation, tunneling adjacent to the existing buildings and utilities, and cut-and-cover construction in urban environment characterize the design challenges of the CLT. This paper presents the design approach for the Preliminary Engineering of the CLT and describes the current proposed design and construction methodology. Different alternatives for the CLT including double-track large-diameter TBM-bored tunnel, single-track twin TBM-bored tunnels, and mined (NATM) tunnel are discussed in this paper. The paper also discusses ground water control during construction, tunnel muck removal, and brief description on numerical modeling and tunnel structural design

Spin Curves for MicroChem S1800 (1805, 1813, 1818) Series Positive Resist

Spin curves for MicroChem\u27s S1805, S1813, and S1818 were generated and mapped using the Filmetrics F50. Statistical measurements were performed (N=85) and are reported here

Elionix ELS-7500EX: Field Size Analysis

This report documents the field distortion of the Elionix ELS-7500EX electron beam lithography system at the University of Pennsylvania Singh Center for Nanotechnology at the Quattrone Nanofabrication Facility. The system is equipped with a 20MHz fixed clock and fixed focus. The aim of the work is to understand optimal field sizes to use for critical dimensions 80nm and above. Field uniformity was analyzed as a function of critical dimension and objective lens aperture (OLA) a.k.a. final paerture. As features scale down below 300nm, they are more susceptible to the systematic effects of field distortion. Suggested field sizes depend on the feature size that is desired

PMMA A2 Contrast Curves

This report documents the contrast curves for the PMMA A2 electron beam lithography resist from MicroChem. Spin curves for PMMA A2 can be found in previous work. The aim is to provide an approximate clearing and base dose for the PMMA A2 standard process at the Singh Center for Nanotechnology